/*
 * $Header:
 * /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons
 * //httpclient/src/java/org/apache/commons/httpclient/HttpVersion.java,v 1.6
 * 2004/12/20 19:52:50 olegk Exp $ $Revision: 480424 $ $Date: 2006-11-29
 * 06:56:49 +0100 (Wed, 29 Nov 2006) $
 *
 * ====================================================================
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many individuals on
 * behalf of the Apache Software Foundation. For more information on the Apache
 * Software Foundation, please see <http://www.apache.org/>.
 */

package com.microsoft.tfs.core.httpclient;

/**
 * <p>
 * HTTP version, as specified in RFC 2616.
 * </p>
 * <p>
 * HTTP uses a "&lt;major&gt;.&lt;minor&gt;" numbering scheme to indicate
 * versions of the protocol. The protocol versioning policy is intended to allow
 * the sender to indicate the format of a message and its capacity for
 * understanding further HTTP communication, rather than the features obtained
 * via that communication. No change is made to the version number for the
 * addition of message components which do not affect communication behavior or
 * which only add to extensible field values. The &lt;minor&gt; number is
 * incremented when the changes made to the protocol add features which do not
 * change the general message parsing algorithm, but which may add to the
 * message semantics and imply additional capabilities of the sender. The
 * &lt;major&gt; number is incremented when the format of a message within the
 * protocol is changed. See RFC 2145 [36] for a fuller explanation.
 * </p>
 * <p>
 * The version of an HTTP message is indicated by an HTTP-Version field in the
 * first line of the message.
 * </p>
 *
 * <pre>
 *     HTTP-Version   = "HTTP" "/" 1*DIGIT "." 1*DIGIT
 * </pre>
 * <p>
 * Note that the major and minor numbers MUST be treated as separate integers
 * and that each MAY be incremented higher than a single digit. Thus, HTTP/2.4
 * is a lower version than HTTP/2.13, which in turn is lower than HTTP/12.3.
 * Leading zeros MUST be ignored by recipients and MUST NOT be sent.
 * </p>
 *
 * @author <a href="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
 *
 * @version $Revision: 480424 $ $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov
 *          2006) $
 *
 * @since 3.0
 */
public class HttpVersion implements Comparable {

    /** Major version number of the HTTP protocol */
    private int major = 0;

    /** Minor version number of the HTTP protocol */
    private int minor = 0;

    /** HTTP protocol version 0.9 */
    public static final HttpVersion HTTP_0_9 = new HttpVersion(0, 9);

    /** HTTP protocol version 1.0 */
    public static final HttpVersion HTTP_1_0 = new HttpVersion(1, 0);

    /** HTTP protocol version 1.1 */
    public static final HttpVersion HTTP_1_1 = new HttpVersion(1, 1);

    /**
     * Create an HTTP protocol version designator.
     *
     * @param major
     *        the major version number of the HTTP protocol
     * @param minor
     *        the minor version number of the HTTP protocol
     *
     * @throws IllegalArgumentException
     *         if either major or minor version number is negative
     */
    public HttpVersion(final int major, final int minor) {
        if (major < 0) {
            throw new IllegalArgumentException("HTTP major version number may not be negative");
        }
        this.major = major;
        if (minor < 0) {
            throw new IllegalArgumentException("HTTP minor version number may not be negative");
        }
        this.minor = minor;
    }

    /**
     * Returns the major version number of the HTTP protocol.
     *
     * @return the major version number.
     */
    public int getMajor() {
        return major;
    }

    /**
     * Returns the minor version number of the HTTP protocol.
     *
     * @return the minor version number.
     */
    public int getMinor() {
        return minor;
    }

    /**
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        return major * 100000 + minor;
    }

    /**
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }
        if (!(obj instanceof HttpVersion)) {
            return false;
        }
        return equals((HttpVersion) obj);
    }

    /**
     * Compares this HTTP protocol version with another one.
     *
     * @param anotherVer
     *        the version to be compared with.
     *
     * @return a negative integer, zero, or a positive integer as this version
     *         is less than, equal to, or greater than the specified version.
     */
    public int compareTo(final HttpVersion anotherVer) {
        if (anotherVer == null) {
            throw new IllegalArgumentException("Version parameter may not be null");
        }
        int delta = getMajor() - anotherVer.getMajor();
        if (delta == 0) {
            delta = getMinor() - anotherVer.getMinor();
        }
        return delta;
    }

    /**
     * @see java.lang.Comparable#compareTo(java.lang.Object)
     */
    @Override
    public int compareTo(final Object o) {
        return compareTo((HttpVersion) o);
    }

    /**
     * Test if the HTTP protocol version is equal to the given number.
     *
     * @return <tt>true</tt> if HTTP protocol version is given to the given
     *         number, <tt>false</tt> otherwise.
     */
    public boolean equals(final HttpVersion version) {
        return compareTo(version) == 0;
    }

    /**
     * Test if the HTTP protocol version is greater or equal to the given
     * number.
     *
     * @return <tt>true</tt> if HTTP protocol version is greater or equal given
     *         to the given number, <tt>false</tt> otherwise.
     */
    public boolean greaterEquals(final HttpVersion version) {
        return compareTo(version) >= 0;
    }

    /**
     * Test if the HTTP protocol version is less or equal to the given number.
     *
     * @return <tt>true</tt> if HTTP protocol version is less or equal to given
     *         to the given number, <tt>false</tt> otherwise.
     */
    public boolean lessEquals(final HttpVersion version) {
        return compareTo(version) <= 0;
    }

    /**
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        final StringBuffer buffer = new StringBuffer();
        buffer.append("HTTP/");
        buffer.append(major);
        buffer.append('.');
        buffer.append(minor);
        return buffer.toString();
    }

    /**
     * Parses the textual representation of the given HTTP protocol version.
     *
     * @return HTTP protocol version.
     *
     * @throws ProtocolException
     *         if the string is not a valid HTTP protocol version.
     */
    public static HttpVersion parse(final String s) throws ProtocolException {
        if (s == null) {
            throw new IllegalArgumentException("String may not be null");
        }
        if (!s.startsWith("HTTP/")) {
            throw new ProtocolException("Invalid HTTP version string: " + s);
        }
        int major, minor;

        int i1 = "HTTP/".length();
        int i2 = s.indexOf(".", i1);
        if (i2 == -1) {
            throw new ProtocolException("Invalid HTTP version number: " + s);
        }
        try {
            major = Integer.parseInt(s.substring(i1, i2));
        } catch (final NumberFormatException e) {
            throw new ProtocolException("Invalid HTTP major version number: " + s);
        }
        i1 = i2 + 1;
        i2 = s.length();
        try {
            minor = Integer.parseInt(s.substring(i1, i2));
        } catch (final NumberFormatException e) {
            throw new ProtocolException("Invalid HTTP minor version number: " + s);
        }
        return new HttpVersion(major, minor);
    }

}
